There is an image of this
cultivar on the
Hosta Library. From the photo on the HL website, it appears to be a very
size hosta with green leaves and light creamy yellow
marginal variegation and red dotted petioles. This non-registered cultivar was
originated in Japan.
Mikiko Lockwood in an article on The Hosta Library titled,
A Little About Japanese Hosta Terms defines the term iwa as rock, Iwa Giboshi or
H. longipes, the term fukurin as margined or edged. and the term urajiro as white-backed or white underside.